The Walnut:: 2002 was a rough year for Jack Welch and Jack Grubman. The former CEO of General Electric Corp. and Salomon Smith Barney’s chief telecomm analyst were enmeshed in embarrassing scandals involving adultery and overheated stock ratings.But in 2003, the two Jacks have a chance to redeem themselves via their own reality television shows that will debut later this year. Jack Grubman’s struggles teaching nursery school on an Indian reservation in Northern Arizona will be documented by the Learning Channel beginning this spring. “When Jack yells at those kids, you know he’s also yelling at himself,” says one of the show’s executives.